Gas turbine engines are used to power aircraft, watercraft, power generators, and the like. Gas turbine engines typically include a compressor, a combustor, and a turbine. The compressor compresses air drawn into the engine and delivers high pressure air to the combustor. In the combustor, fuel is mixed with the high-pressure air and is ignited. Products of the combustion reaction in the combustor are directed into the turbine where work is extracted to drive the compressor and, sometimes, an output shaft. Leftover products of the combustion are exhausted out of the turbine and may provide thrust in some applications.
Modern gas turbine engines produce high gas temperature environments that are typically above the melting temperature of the internal hardware. In order to survive in these conditions, turbine hardware typically uses a combination of cooling mechanisms to maintain an acceptable temperature. These mechanisms may include film cooling, thermal barrier coatings (TBC), and internal cooling devices. For airfoils, the stagnation point of the leading edge is an area of the highest gas pressure and highest thermal loads. The zone around the stagnation point is therefore a difficult region to cool due to reduced film effectiveness and potential blockage with debris at outlet ports because of the high gas pressure. Film cooling can be costly in terms of stage efficiency, especially in high Mach regions, and large volumes of cooling air are required for present internal cooling devices. Thus, a need exists for improved devices and methods for airfoil cooling.